Cross-section of centrifuge rotors, new and with deposited particle ‘cake

Diesel engines in commercial vehicles must meet ever stricter legal limits on exhaust emissions. The corresponding improvements in injection and combustion processes do indeed lead to a reduction in emission levels but on the other hand, ingress of soot into the engine oil is substantially increased, for example through exhaust gas recirculation. Soot makes the oil more viscous and less effective as a lubricant.

One tried and tested technique to remove soot particles from the engine oil is bypass oil cleaning using centrifuges. MANN+HUMMEL is a global leader in the manufacture of bypass centrifuges, supplying to the OE sector a combination of main flow filter and oil centrifuge with disposable centrifuge rotor. The centrifuge supports the main flow filter and removes from the engine oil even the finest particles, such as very hard and thus extremely abrasive soot particles which can frequently be up to 100 times smaller than a human hair in diameter. MANN-FILTER supplies these rotors in OE quality to the independent aftermarket.

How does the oil centrifuge work?The centrifuge rotor is driven by the pressure of the engine oil and reaches rotation speeds of up to 11,000 revolutions per minute. The centrifugal forces thus generated, which are over 2,000 times the force of gravity, remove metallic particles from engine abrasion/wear, soot created during the combustion process and dirt from the intake air. These particles are picked up and compacted on the inner wall of the rotor.

The centrifuge rotors from MANN-FILTER consist of metal or plastic. The metal rotors provide higher separation efficiency which is sustained until the capacity limit is reached. Spiral ribs inside the centrifuge cause the engine oil to rotate at the same peripheral speed as the rotor. The greater forces thus generated hurl contaminant particles onto the inner wall of the rotor and in this way reduce the higher levels of soot in the lubricating oil of modern diesel truck engines. The company has been granted a patent for these spiral ribs in Germany and the U.S.

Easier servicing and environmentally-friendly disposal The design of almost all MANN+HUMMEL centrifuges allows simple replacement of the disposable rotors. The rotor can be easily changed as soon as it is filled with contaminant particles. In addition, plastic rotors can be completely incinerated and can thus be recycled in an environmentally-friendly and economical way.

‘The MANN+HUMMEL centrifuges can however offer further benefits’, according to David Purcell, Vice President Business Segment Centrifuge at MANN+HUMMEL. ‘They keep the engine oil clean and an efficient lubricant for a longer period of time, and with regard to the soot content, they extend oil change intervals, which in turn improves downtime. They also reduce wear on critical engine components and thus prolong the service life of the engine’.

About MANN+HUMMELThe MANN+HUMMEL Group is a leading global expert for filtration solutions and development partner and original equipment supplier to the international automotive and mechanical engineering industries. Employing 14,575 people at more than 50 locations worldwide, the company achieved turnover of about 2.6 billion euros in 2012. The group’s product portfolio includes air filter systems, intake manifold systems, liquid filter systems, cabin filters and plastic sound components (known as 'symposers'), as well as filter elements for vehicle servicing and repair. For general engineering, process engineering and industrial manufacturing sectors the company’s product range includes industrial filters, a series of products to reduce carbon emission levels in diesel engines, membrane filters for water filtration and filter systems.